Help! I've fallen and can't get up(graded).

I'm getting confused and frustrated. Bummed to learn that Leopard (sans Snow) is highest OS my 2005 powerbook G4 with OSX 4.5.11 can handle. [Thank you Intel] But do I have to buy a Leopard DVD to install it? Is there some "free-ish" place where I can download the Leopard OS as an upgrade and install it over my existing OS system?

I are befuddled!

There is no place to legally get free upgrades across major OSX releases. You will need to purchase a Leopard disc and then upgrade freely with Software Update to 10.5.8..

And alas be prepared to outlay more than $100 for a used disc. Then if Apple follows usual system of dropping support, updates etc when two releases old, will be dropped in a month or two.

It'd be easier to sell your Powerbook and buy a refurbished MacBook 13" from Refurbished Mac Computers - Refurbished Laptops, Notebooks & Desktop Computers - Apple Store (U.S.).